use std::io;
use rand::Rng;
use std::cmp::Ordering;

fn main() {
    println!("Guess the number!");

    let secret_number = rand::thread_rng().gen_range(1..=100);

    // println!("The secret number is: {secret_number}");

    loop {
        println!("Please input your guess.");

        let mut guess = String::new(); //mut 表示可变变量
        
        io::stdin()
            .read_line(&mut guess) // &mut 表示可变引用
            .expect("Failed to read line");

        // let guess: u32 = guess.trim().parse().expect("Please type a number!"); //相同变量名，类型覆盖
        let guess: u32 = match guess.trim().parse() {
            Ok(num) => num,
            Err(_) => {
                println!("⚠️ Please type a number!");
                continue;
            },
        }; //捕获异常，程序继续，而不会崩溃退出

        println!("You guessed: {guess}");

        match guess.cmp(&secret_number) {
            Ordering::Less => println!("Too small!"),
            Ordering::Greater => println!("Too big!"),
            Ordering::Equal => {
                println!("You win!");
                break;
            }
        }
    }

    // let x = 5;
    // let y = 10;

    // println!("x = {x} and y = {y}, x + y = {}", x + y);

}